Controlled steering or directional drilling techniques are commonly used in the oil, water, and gas industry to reach resources that are not located directly below a wellhead. The advantages of directional drilling are well known and include the ability to reach reservoirs where vertical access is difficult or not possible (e.g. where an oilfield is located under a city, a body of water, or a difficult to drill formation) and the ability to group multiple wellheads on a single platform (e.g. for offshore drilling).
Directional drilling devices often utilize a plurality of steering devices arranged in a circle on the exterior surface of a drill string. These steering devices need to be cyclically actuated to achieve steering in desired direction. Conventional control systems for steering devices are unnecessarily complicated and often include a valve for each steering device (e.g., three valves are required to control three steering devices). Accordingly, there is a need for simpler control systems.